The objectives of the Registry of Experimental Cancers are to acquire, preserve and retrieve pathological materials and records representing cases of experimentally induced and spontaneous cancers and other lesions of laboratory animals. These materials are used for educational and research purposes. Two veterinary pathologists have been added to the staff of the Registry. This year, 977 new accessions were processed either singly or in groups. Among these were many cases with unique or rare diagnoses. Storage space for the histologic slides and records continues in building 41 while storage space for the paraffin blocks has been relocated to an off-site warehouse in Frederick, MD. This year the Registry has completed the transfer of the entire WYLBUR Registry database to a new object oriented sofware program loaded into a 486 25 MHz personal computer located in the Registry offices. This program allows for effective and rapid retrieval of data, search capabilities and production of printouts on specific data requests. As determined by an exhaustive search of the database, the total number of accessions in the Registry is 60,325. Prior to the advent of this computer program, only rough estimates of the total number of cases was possible. The pathologic materials and data are used to develop study sets of histologic slides and accompanying syllabi. In addition to 16 sets currently available, two new study sets are near completion and several others have been started. This year 119 study sets were distributed world wide among investigators and students of experimental carcinogenesis, toxicology and comparative pathology. In this regard the Registry functions as the only World Health Organization's Collaborating Centre for Reference on Tumours of Laboratory Animals. The data and materials are also used by the Registry staff and by visitors to the Registry for study and research. There have been single or multiple visits by 49 investigators.